Question

What is the smallest constituent of matter that retains its chemical identity?
(A) Atom
(B) Molecule
(C) Ion
(D) Radical

Answer 1

Hint: Matter can be anything that is present around us. Matter can be defined as any substance or thing that has mass and occupies space (has volume). Every compound or matter is made up of small units collectively which are further indivisible and retain the chemical properties of the matter or substance.

Complete answer:
Matter can be considered as anything that is present around us. So, we can say that it can be defined as any substance or thing that has mass and occupies space (has volume).
Every compound or matter is made up of small units collectively which are further indivisible and retain the chemical properties of the matter or substance.
So, an atom is considered as the smallest constituent of matter that retains the chemical properties. Molecules are made up of two or more different atoms collectively. While radicals and the ions have different chemical identity from that of pure matter or substance.
We know that atoms further consist of protons, electrons and neutrons but they cannot exist independently and do not retain the chemical identity of matter.
So, we can say that an atom is considered as the smallest constituent of matter that retains its chemical identity.
Hence, the correct option is: (A) Atom.

Note:
Radicals are formed when an atom loses its one electron and an unpaired electron remains in its valence orbitals. Ions (charged species) form when the atom loses or gains electrons. The positively charged ion is known as cation and the negatively charged ion is known as anion. These are very reactive in nature.